WASHINGTON (CNN) -- Sen. Hillary Clinton on Tuesday said Sen. Barack Obama had become frustrated by his losses in New Hampshire and Nevada, and she also accused her opponent of not backing up his words with action.

Obama responded quickly, saying Clinton was willing to "fudge the truth" in her quest for the Democratic presidential nomination.

The bitter exchange continued the sharp confrontations from Monday night's Democratic debate in Myrtle Beach, South Carolina.

The sniping came four days before Saturday's Democratic primary in South Carolina.

This first Democratic primary in the South is crucial. It's the candidates' last contest before the Super Tuesday primaries February 5 in which voters cast ballots in 24 states.

"Sen. Obama is very frustrated," Clinton told reporters in Washington."The events of the last 10 or so days, particularly the outcomes of New Hampshire and Nevada, have apparently convinced him to adopt a different strategy.

Don't Miss

"Clearly, I believe that words matter, but I think actions matter more," Clinton said. "And time and time again we see where the words and actions don't match, and I think there were a number of examples of that last night."

Clinton also said Obama's "present" votes as an Illinois state senator showed an unwillingness to make difficult choices.

"I think you saw that both Sen. Edwards and I don't believe you can vote 'present' as president," she said, referring to former Sen. John Edwards, the other candidate in Monday's debate. "The buck stops in the Oval Office. You have to make these tough decisions; it has to be yes or no. Maybe is not an option."

Responding to Clinton's comments during a conference call with reporters Tuesday, Obama said the senator from New York and former President Clinton have been "attacking me in ways that are not accurate."

"Sen. Clinton announced while we were still in Iowa that this was going to be her strategy and called it the 'fun part' of campaigning. I don't think it's the fun part to fudge the truth," he said. Watch Obama fire back at Clinton »

"If you get the kind of looseness with the facts that Sen. Clinton's displayed and you're willing to say anything to get a political or tactical advantage, that erodes people's trust in government. It makes them cynical," Obama said.

"It's important for our campaign to not only make sure the record is correct when folks are saying things that don't jive with the facts but also that we are sending a message to voters that we're going to bring about a different kind of politics over the long term."

The exchanges saw the two interrupting each other and turning to direct their responses to each other instead of the panel of moderators.

"It is very difficult having a standup debate with you because you never take responsibility for any vote," Clinton said. She accused Obama of not supporting a Senate amendment that would have capped the interest rate on credit cards at 30 percent. "It's just very difficult to get a straight answer."

The comment drew boos from Obama supporters.

Obama said Clinton had worked as "a corporate lawyer sitting on the board of Wal-Mart" while he was a community organizer. Clinton jabbed Obama for representing a slumlord when he was a lawyer in Chicago.

The exchanges allowed Edwards, a South Carolina native, to cast himself as the candidate more interested in policy discussions than political sniping.

"Between all the allegations for Hillary serving on the Wal-Mart board, and Sen. Obama working for a slumlord, I was proud to represent the grown-up wing of the Democratic Party last night," Edwards told supporters during a rally Tuesday in Conway, South Carolina.

"All those kind of personal attacks going on, it doesn't do a thing to get somebody health care that doesn't have health care, it doesn't do a thing to get kids the kind of education that they need. We have work to do in this country."

When asked about the recent exchanges between his wife and Obama, former President Clinton said voters ask him about the economy, the war in Iraq and national security concerns, not about "the inevitable back-and-forth that happens in every campaign."

"Sometimes when you have a family feud it's harsher than if you have a feud with a family in another clan because you have to dig so hard to get to where the differences are," he said while campaigning for his wife in Columbia, South Carolina, Tuesday.

A recent national poll showed 59 percent of black Democrats backing Obama, compared with 31 percent for Clinton. The support marks a sharp increase from the early days of the campaign and may be a big factor in South Carolina, where as many as half the voters in the Democratic primary will be African-Americans.

Clinton, who scored victories in the New Hampshire primary and Nevada caucuses, could use a win in the state to paint herself as the clear front-runner going into Super Tuesday.

Obama, who won the Iowa caucuses, would shift momentum to himself after Clinton's back-to-back wins, while Edwards needs a victory to shed his image as a perennial third-place finisher.E-mail to a friend